Scattered pilot correlation in DVB-H systems

Abstract

A method for correlating scattered pilot locations in a sequence of OFDM symbols in a multi-carrier transmission system, and includes mapping pilot locations comprising pilot symbols having predetermined known values, wherein the pilot symbols are positioned among data subcarriers in time and frequency dimensions consisting of received pilot symbols and having a predetermined position pattern in the time and frequency dimensions, wherein the predetermined position pattern comprises a finite number of sub-position patterns each corresponding to positions of the pilot symbols; estimating a Doppler spread in a frequency spectrum between the transmitter and the receiver in the multi-carrier transmission system; estimating a channel length of a set of channel paths received at the receiver; and the receiver automatically selecting one of a plurality of predetermined methods of correlating the scattered pilot locations in the sequence of OFDM symbols based only on the estimating processes.

1. A method for correlating scattered pilot locations in a sequence of orthogonal-frequency-division-multiplexing (OFDM) symbols transmitted by a transmitter and received by a receiver in a multi-carrier transmission system, said OFDM symbols comprising continuous pilot symbols and scattered pilot symbols, said method comprising:
 mapping pilot locations comprising pilot symbols having predetermined known values, wherein said pilot symbols are positioned among data subcarriers in time and frequency dimensions consisting of received pilot symbols and having a predetermined position pattern in said time and frequency dimensions, wherein said predetermined position pattern comprises a finite number of sub-position patterns each corresponding to positions of said pilot symbols; 
 estimating a Doppler spread in a frequency spectrum between said transmitter and said receiver in said multi-carrier transmission system; 
 estimating a channel length of a set of channel paths received at said receiver; 
 providing a predetermined method of correlating said scattered pilot locations in said sequence of OFDM symbols; and 
 said receiver automatically selecting said predetermined method of correlating said scattered pilot locations in said sequence of OFDM symbols based only on the estimating processes, wherein the selecting process comprises:
 grouping a range of all pilot symbols located in a single subcarrier corresponding to a dynamic time dimension and a single frequency dimension, wherein said range comprises all pilot symbols located between and including a first received scattered pilot symbol and a last received scattered pilot symbol received in a single subcarrier; 
 buffering said range of all pilot symbols located in a single subcarrier; 
 disregarding a change in subcarrier values across said range of all pilot symbols located in a single subcarrier; 
 creating a graphical pilot correlation sequence corresponding to the buffered range of all pilot symbols located in a single subcarrier; 
 locating peaks in said pilot correlation sequence; and 
 identifying said peaks as scattered pilot symbol locations. 
 
 
     
     
       2. The method of  claim 1 , wherein said multi-carrier transmission system comprises a Digital Video Broadcasting-Handheld (DVB-H) system. 
     
     
       3. The method of  claim 1 , wherein said range of all pilot symbols located in a single subcarrier equals four pilot symbols. 
     
     
       4. The method of  claim 1 , wherein said OFDM symbols are received in a slow fading channel. 
     
     
       5. The method of  claim 1 , wherein said buffering of said range of all pilot symbols located in a single subcarrier comprises buffering four received OFDM symbols. 
     
     
       6. A method comprising:
 providing orthogonal-frequency-division-multiplexing (OFDM) symbols comprising continuous pilot symbols and scattered pilot symbols; 
 mapping pilot locations comprising pilot symbols having predetermined known values, wherein said pilot symbols are positioned among data subcarriers in time and frequency dimensions comprising received pilot symbols and having a predetermined position pattern in said time and frequency dimensions, wherein said predetermined position pattern comprises a finite number of sub-position patterns each corresponding to positions of said pilot symbols; 
 estimating a Doppler spread in a frequency spectrum in a multi-carrier transmission system; 
 estimating a channel length of a set of channel paths; 
 providing a predetermined method of correlating said scattered pilot locations in said sequence of OFDM symbols; and 
 automatically selecting said predetermined method of correlating said scattered pilot locations in said sequence of OFDM symbols based only on the estimating processes, wherein the selecting process comprises:
 grouping a range of all pilot symbols located in a single subcarrier corresponding to a dynamic time dimension and a single frequency dimension, wherein said range comprises all pilot symbols located between and including a first received scattered pilot symbol and a last received scattered pilot symbol received in a single subcarrier; 
 buffering said range of all pilot symbols located in a single subcarrier; 
 disregarding a change in subcarrier values across said range of all pilot symbols located in a single subcarrier; 
 creating a graphical pilot correlation sequence corresponding to the buffered range of all pilot symbols located in a single subcarrier; 
 locating peaks in said pilot correlation sequence; and 
 identifying said peaks as scattered pilot symbol locations. 
 
 
     
     
       7. The method of  claim 6 , wherein said multi-carrier transmission system comprises a Digital Video Broadcasting-Handheld (DVB-H) system. 
     
     
       8. The method of  claim 6 , wherein said range of all pilot symbols located in a single subcarrier equals four pilot symbols. 
     
     
       9. The method of  claim 6 , wherein said OFDM symbols are received in a slow fading channel. 
     
     
       10. The method of  claim 6 , wherein said buffering of said range of all pilot symbols located in a single subcarrier comprises buffering four received OFDM symbols. 
     
     
       11. A method for correlating scattered pilot locations in a sequence of orthogonal-frequency-division-multiplexing (OFDM) symbols received by a receiver in a multi-carrier transmission system, said OFDM symbols comprising continuous pilot symbols and scattered pilot symbols, said method comprising:
 mapping pilot locations comprising pilot symbols having predetermined known values, wherein said pilot symbols are positioned among data subcarriers in time and frequency dimensions comprising received pilot symbols and having a predetermined position pattern in said time and frequency dimensions, wherein said predetermined position pattern comprises a finite number of sub-position patterns each corresponding to positions of said pilot symbols; 
 estimating a Doppler spread in a frequency spectrum in said multi-carrier transmission system; 
 estimating a channel length of a set of channel paths received at said receiver; 
 providing a plurality of predetermined methods of correlating said scattered pilot locations in said sequence of OFDM symbols; and 
 automatically selecting one of said plurality of predetermined methods of correlating said scattered pilot locations in said sequence of OFDM symbols based only on the estimating processes, wherein the selecting process comprises:
 grouping a range of all pilot symbols located in a single subcarrier corresponding to a dynamic time dimension and a single frequency dimension, wherein said range comprises all pilot symbols located between and including a first received scattered pilot symbol and a last received scattered pilot symbol received in a single subcarrier; 
 buffering said range of all pilot symbols located in a single subcarrier; 
 disregarding a change in subcarrier values across said range of all pilot symbols located in a single subcarrier; 
 creating a graphical pilot correlation sequence corresponding to the buffered range of all pilot symbols located in a single subcarrier; 
 locating peaks in said pilot correlation sequence; and 
 identifying said peaks as scattered pilot symbol locations. 
 
 
     
     
       12. The method of  claim 11 , wherein said multi-carrier transmission system comprises a Digital Video Broadcasting-Handheld (DVB-H) system. 
     
     
       13. The method of  claim 11 , wherein said range of all pilot symbols located in a single subcarrier equals four pilot symbols. 
     
     
       14. The method of  claim 11 , wherein said OFDM symbols are received in a slow fading channel. 
     
     
       15. The method of  claim 11 , wherein said buffering of said range of all pilot symbols located in a single subcarrier comprises buffering four received OFDM symbols.